Sleeve Device For Transferring Bending Moments

ABSTRACT

A sleeve device for transferring bending moments induced in a reinforced concrete slab includes a generally hollow member and tension rebars. The hollow member is positioned and fastened on a bottom formwork defining the reinforced concrete slab. The tension rebars are connected to opposing sides of an upper portion of the hollow member either directly or using rebar connectors. The hollow member creates a void in the reinforced concrete slab by pouring of concrete around an outer wall of the hollow member. The hollow member transfers compressive stresses across a bottom of the hollow member and tensile stresses through the tension rebars and the upper portion of the hollow member. The affixed tension rebars are spliced with regular reinforced concrete slab rebars to develop tensile stresses that are transferred through the relatively stiffer hollow member to retain a slab moment capacity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of provisional patent application No. 61/846,079 titled “Sleeve Device For Transferring Bending Moments”, filed in the United States Patent and Trademark Office on Jul. 15, 2013. The specification of the above referenced patent application is incorporated herein by reference in its entirety.

BACKGROUND

The apparatus disclosed herein, in general, relates to sleeves for concrete structures. More particularly, the apparatus disclosed herein relates to a sleeve device that transfers bending moments induced in a reinforced concrete slab and compensates for reinforced concrete slab moment capacity loss due to penetrations proximal to concrete columns.

Reinforced concrete flat slabs are extensively used in concrete construction. During a manufacturing process, utility pipes are typically positioned adjacent to concrete columns due to architectural or mechanical constraints. To position a utility pipe through a reinforced concrete slab, holes are created in the reinforced concrete slab. There are several conventional methods employed to create holes in cast-in-place concrete slabs. One method for creating a hole in a cast-in-place concrete slab is by using a formwork that includes a section defining a hole positioned in a specified location inside the formwork. Concrete is poured inside the formwork around the section that defines the hole to create a reinforced concrete slab with a hole. After the concrete is cured, the formwork is removed.

Another conventional method to form a void during the concrete pour is to use sleeves. The sleeves are retained in the reinforced concrete slab. Although the voids created using this method allow mechanical piping to run through the reinforced concrete slab, these voids reduce the structural capability of the concrete and the sleeves. The sleeves are generally made of tube shaped steel that offers no structural capacity due to a lack of bond between concrete and steel tubes. Since pipe penetrations tend to cut or displace top rebars and bottom rebars, the moment capacity of reinforced concrete slabs is reduced and in some cases causes flexural failures. In some cases, multiple sleeves are placed in proximity to a column and design engineers cannot accommodate the moment capacity requirements to attain the minimum code prescribed rebar spacing. Therefore, design engineers often have to check moment and shear capacities of the concrete slabs when the sleeves are placed in close proximity to slab supports such as concrete columns. In many cases, structural modifications are required to compensate for the loss of moment capacity caused by pipe penetrations. The structural modifications comprise, for example, increasing slab thickness, positioning extra rebars on both sides of the penetrations, etc.

Hence, there is a long felt but unresolved need for a sleeve device that reinforces concrete slabs while allowing penetrations in close proximity to slab supports such as concrete columns, adding structural capacity to the concrete slabs, and minimizing the work and effort required from an engineer, thereby allowing architects and mechanical engineers more flexibility in positioning mechanical piping.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts in a simplified form that are further disclosed in the detailed description of the invention. This summary is not intended to identify key or essential inventive concepts of the claimed subject matter, nor is it intended for determining the scope of the claimed subject matter.

The sleeve device disclosed herein addresses the above stated needs for reinforcing concrete slabs while allowing penetrations in close proximity to slab supports, for example, concrete columns. The sleeve device disclosed herein transfers bending moments induced in a reinforced concrete slab and compensates for reinforced concrete slab moment capacity loss due to penetrations proximal to concrete columns. The sleeve device disclosed herein adds structural capacity to concrete slabs, minimizes the work and effort required from an engineer, and allows architects and mechanical engineers more flexibility in positioning mechanical piping. The sleeve device is a device, for example, made of metal attached to and cast within a concrete structure such as a reinforced concrete slab and is configured to transfer bending moments induced in the reinforced concrete slab. The sleeve device disclosed herein comprises a generally hollow member and tension rebars. The hollow member is positioned on and fastened to a bottom formwork defining a reinforced concrete slab. The tension rebars are connected to opposing sides of an upper portion of the hollow member either directly or using rebar connectors. The hollow member is configured to create a void in the reinforced concrete slab by pouring of concrete around an outer wall of the hollow member. The hollow member is further configured to transfer compressive stresses across a bottom of the hollow member and tensile stresses through the tension rebars and the upper portion or the top of the hollow member. The tensile stresses or forces are transferred through the tension rebars and the relatively stiffer hollow member to the opposing side of the hollow member.

The tension rebars connected to the opposing sides of the hollow member are configured to be spliced with regular reinforced concrete slab rebars in accordance with a standard rebar tension splice length for transferring the bending moments induced in the reinforced concrete slab. The bending moments in the reinforced concrete slab are resisted by tensile stresses in the tension rebars and the compressive stresses in the concrete. The tensile stresses in the tension rebars on both sides of the hollow member are transferred into the relatively stiffer hollow member, and the tensile stresses acting on the opposing sides of the hollow member are balanced out through the outer wall of the hollow member, thereby bridging the two tensile stresses from the tension rebars.

After concrete is cast around the sleeve device, the sleeve device is embedded in the reinforced concrete slab and works together with the rest of the reinforced concrete slab. The tensile stresses due to the bending moments are transferred to one of the tension rebars on one opposing side of the hollow member, then through the hollow member, to the other tension rebar on the other opposing side of the hollow member, and then to the regular reinforced concrete slab rebars spliced with the tension rebars.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, exemplary constructions of the invention are shown in the drawings. However, the invention is not limited to the specific methods and structures disclosed herein. The description of a method step or a structure referenced by a numeral in a drawing carries over to the description of that method step or structure shown by that same numeral in any subsequent drawing herein.

FIG. 1A exemplarily illustrates a top perspective view of a sleeve device fastened to a bottom formwork for transferring bending moments induced in a reinforced concrete slab.

FIG. 1B illustrates an enlarged view of a portion marked X in FIG. 1A, showing the sleeve device.

FIG. 2 illustrates a partial sectional view of the sleeve device.

FIG. 3 illustrates a top plan view of the sleeve device.

FIG. 4A exemplarily illustrates an isometric view of an embodiment of the sleeve device, showing tension rebars of the sleeve device configured as corrugated fins fixedly connected to a hollow member of the sleeve device.

FIG. 4B exemplarily illustrates an isometric view of an embodiment of the sleeve device, showing the tension rebars of the sleeve device configured as bent plates fixedly connected to the hollow member of the sleeve device.

FIG. 5A exemplarily illustrates an isometric view of an embodiment of the sleeve device, showing the hollow member of the sleeve device having a square cross section.

FIG. 5B exemplarily illustrates an isometric view of an embodiment of the sleeve device, showing the hollow member of the sleeve device having a rectangular cross section.

FIG. 6 exemplarily illustrates a side view of the sleeve device positioned within a reinforced concrete slab, showing bending moments, tensile stresses, and compressive stresses acting on the reinforced concrete slab.

FIG. 7A exemplarily illustrates an isometric wireframe view, showing deformed rebars of the sleeve device in a different orientation within a concrete beam.

FIG. 7B illustrates an enlarged view of a portion marked Y in FIG. 7A, showing deformed rebars in a different orientation within the concrete beam.

FIG. 8 exemplarily illustrates a top plan view, showing splicing of deformed rebars of two sleeve devices with top rebars of the reinforced concrete slab.

FIG. 9A exemplarily illustrates an isometric view of multiple sleeve devices positioned in a reinforced concrete slab supported by a supporting column.

FIG. 9B illustrates an enlarged view of a portion marked Z in FIG. 9A.

FIG. 10 illustrates a method for transferring bending moments induced in a reinforced concrete slab.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A exemplarily illustrates a top perspective view of a sleeve device 100 fastened to a bottom formwork 108 for transferring bending moments induced in a reinforced concrete slab 601 exemplarily illustrated in FIG. 6 and FIG. 7A. A bending moment is a measure of the average internal stress induced in the reinforced concrete slab 601 when an external force or moment is applied to the reinforced concrete slab 601 causing the reinforced concrete slab 601 to bend. As used herein, “bending moment” in a reinforced concrete slab 601 refers to an algebraic sum of moments of all bending forces acting on the reinforced concrete slab 601 due to the self-load of concrete 109 poured around the sleeve device 100 and an additional load positioned on the reinforced concrete slab 601. FIG. 1B illustrates an enlarged view of a portion marked X in FIG. 1A, showing the sleeve device 100. The sleeve device 100 disclosed herein is a cast-in-place sleeve device, for example, made of steel and used in a concrete structure, for example, a reinforced concrete slab 601, to transfer moments due to gravity loads, seismic loads, and wind loads by mechanically attaching a bottom rebar, a top rebar 802 exemplarily illustrated in FIG. 8, or a combination of the bottom rebar and the top rebar 802 of the reinforced concrete slab 601 to opposing sides 101 d and 101 e of the sleeve device 100.

The sleeve device 100 disclosed herein comprises a generally hollow member 101 and tension rebars, for example, 103 and 104. As used herein, “tension rebars” refer to reinforcing steel bars used to transfer tensile stresses in concrete construction. Also, as used herein, “tensile stress” refers to a tensile force acting per unit cross sectional area of a tension rebar, for example, 103 or 104 due to bending moments on sections of the reinforced concrete slab 601. In an embodiment as exemplarily illustrated in FIGS. 1A-3, the tension rebars are configured as deformed rebars 103 and 104 fixedly connected to the opposing sides 101 d and 101 e of an upper portion 101 a of the hollow member 101 to transfer the tensile stresses to and from the hollow member 101 to the tension rebars.

In an embodiment as exemplarily illustrated in FIGS. 1A-4B, the hollow member 101 is of a generally cylindrical shape. The hollow member 101 is positioned on and fastened to a bottom formwork 108 defining the reinforced concrete slab 601. The hollow member 101 is configured to create a void 102 in the reinforced concrete slab 601 by pouring of concrete 109 around an outer wall 101 c of the hollow member 101. The void 102 created by the hollow member 101 can be of multiple geometric shapes that allow components, for example, piping, duct work, air passages, fluid passages, etc., to pass through, or for visual purposes, or for other architectural or mechanical needs. The thickness of the hollow member 101 is checked and configured to avoid local yielding of the outer wall 101 c of the hollow member 101. The hollow member 101 is further configured to transfer compressive stresses 604 exemplarily illustrated in FIG. 6, across a bottom or a lower portion 101 b of the hollow member 101 and tensile stresses 603 exemplarily illustrated in FIG. 6, through the deformed rebar, for example, 103 and an upper portion 101 a or the top of the hollow member 101. As used herein, “compressive stress” refer to a compression force acting per unit cross sectional area at the bottom or a lower portion 101 b of the hollow member 101 due to bending moments acting on sections of the reinforced concrete slab 601.

In an embodiment, the sleeve device 100 further comprises rebar connectors 105 and 106. The rebar connectors 105 and 106 are operably connected on the opposing sides 101 d and 101 e of the upper portion 101 a of the hollow member 101. The rebar connectors 105 and 106 fixedly connect the deformed rebars 103 and 104 respectively, to the opposing sides 101 d and 101 e of the upper portion 101 a of the hollow member 101. The deformed rebars 103 and 104 are, for example, threaded rebars or reinforced bars used in concrete construction and configured to support the load of the concrete 109. In an example, the deformed rebars 103 and 104 exemplarily illustrated in FIGS. 1A-3, can be configured as tension rods. The deformed rebars 103 and 104 are spliced with the top rebars 802 of the reinforced concrete slab 601 exemplarily illustrated in FIG. 8, in accordance with a standard rebar tension splice length 803 exemplarily illustrated in FIG. 8, for transferring the bending moments induced in the reinforced concrete slab 601. As used herein, “standard rebar tension splice length” refers to a length by which two rebars, for example, 104 and 802 exemplarily illustrated in FIG. 8, are overlapped and joined together to create a bond strength equal to a continuous running single rebar. The “standard rebar tension splice length” as defined by the American Concrete Institute (ACI) in Building Code Requirements for Structural Concrete refers to the length required by the ACI 318 to develop the required tensile stress in the rebars, for example, 104 and 802. After the concrete 109 is cured, the sleeve device 100 is embedded in the reinforced concrete slab 601 and works together with the rest of the reinforced concrete slab 601.

The bending moments in the reinforced concrete slab 601 are resisted by the tensile stresses in the deformed rebars 103 and 104 and the compressive stresses in the concrete 109. The tensile stresses in the deformed rebars 103 and 104 on the opposing sides 101 d and 101 e of the hollow member 101 are transferred into the hollow member 101, and the tensile stresses acting on the opposing sides 101 d and 101 e of the hollow member 101 are balanced out through the outer wall 101 c of the hollow member 101, thereby bridging the tensile stresses from the deformed rebars 103 and 104.

As exemplarily illustrated in FIGS. 1A-1B, in an embodiment, the sleeve device 100 disclosed herein further comprises mounting rings 107 rigidly connected to and extending outwardly from the opposing sides 101 g and 101 h of a lower portion 101 b of the hollow member 101. The mounting rings 107 are configured to fasten the hollow member 101 to the bottom formwork 108 defining the reinforced concrete slab 601. The mounting rings 107 comprise holes 110 concentrically bored on the mounting rings 107 to receive fastening elements, for example, nails. The mounting rings 107 rigidly hold the hollow member 101 in place in the bottom formwork 108 to preclude movement of the hollow member 101 prior to pouring of the concrete 109. In an embodiment, the mounting rings 107 for fastening or nailing down the sleeve device 100 may be altered or removed.

In an embodiment, the components of the sleeve device 100 can be of different sizes, for example, can be larger or smaller in size, to accommodate different opening sizes and structural capacities. The rebar connectors 105 and 106 with the deformed rebars 103 and 104 on the opposing sides 101 d and 101 e of the hollow member 101 can be replaced with alternative affixations to transfer bending moments. The materials used for manufacturing the sleeve device 100 are, for example, any high or low strength steel, alloy or other metal, carbon fiber, fiber reinforced polymer, or other structural material. The size of the sleeve device 100 can be increased or decreased depending on the requirements. The sleeve device 100 is configured to be installed on site by unskilled labor without using any special tools.

FIG. 2 illustrates a partial sectional view of the sleeve device 100. The deformed rebars 103 and 104 of the sleeve device 100 are connected at an upper portion 101 a of the hollow member 101 and on opposing sides 101 d and 101 e of the hollow member 101 via the rebar connectors 105 and 106 respectively. A first deformed rebar 103 is connected to one opposing side 101 d of the hollow member 101 and extends outward from the outer wall 101 c of the hollow member 101. Similarly, a second deformed rebar 104 is connected to the other opposing side 101 e of the hollow member 101 and extends outward from the outer wall 101 c of the hollow member 101. The first deformed rebar 103 is located near the upper portion 101 a of the hollow member 101. On the other opposing side 101 e of the hollow member 101, the second deformed rebar 104 extends away from the upper portion 101 a of the hollow member 101. Concrete 109 exemplarily illustrated in FIG. 1A, is cast around the hollow member 101 to create the void 102 in the reinforced concrete slab 601 exemplarily illustrated in FIG. 6.

FIG. 3 illustrates a top plan view of the sleeve device 100. The mounting rings 107 of the sleeve device 100 are rigidly connected at the lower portion 101 b of the hollow member 101 exemplarily illustrated in FIG. 1B, and on diametrically opposing sides 101 g and 101 h of the hollow member 101. The mounting rings 107 are oriented perpendicular to an axis line 111 that passes through the deformed rebars 103 and 104. The mounting rings 107 protruding outwardly from the hollow member 101 affix the hollow member 101 to the bottom formwork 108 of the reinforced concrete slab 601 exemplarily illustrated in FIG. 1A, FIG. 6, and FIG. 7A, so that a bottom base plane 107 a of each of the mounting rings 107 is oriented at the same level as the bottom plane 101 f of the hollow member 101 exemplarily illustrated in FIG. 2. The holes 110 defined in the mounting rings 107 are positioned outside the outer wall 101 c, for example, outside the outer diameter of the hollow member 101. The deformed rebars 103 and 104 are positioned on the outer wall 101 c of the hollow member 101 and midway between the mounting rings 107 that are positioned near the bottom plane 101 f of the hollow member 101.

FIGS. 4A-4B exemplarily illustrate isometric views of different embodiments of the sleeve device 100, showing different configurations of the tension rebars, for example, 112 and 113, and 114 and 115. In an embodiment as exemplarily illustrated in FIG. 4A, the tension rebars of the sleeve device 100 are configured as corrugated fins 112 and 113 fixedly connected to the hollow member 101 of the sleeve device 100 for transferring tensile stresses to and from the hollow member 101. In another embodiment as exemplarily illustrated in FIG. 4B, the tension rebars of the sleeve device 100 are configured as bent plates 114 and 115 fixedly connected to the hollow member 101 of the sleeve device 100 for transferring the tensile stresses to and from the hollow member 101.

Although the detailed description refers to the tension rebars of the sleeve device 100 configured as deformed rebars 103 and 104, corrugated fins 112 and 113, and bent plates 114 and 115 for transferring the tensile stresses to and from the hollow member 101, the scope of the sleeve device 100 disclosed herein is not limited to the tension rebars being configured as deformed rebars 103 and 104, corrugated fins 112 and 113, and bent plates 114 and 115, but may be extended to include tension rebars configured as tension rods, corrugated plates, straight bars, angles, pins, wire meshes, synthetic materials, etc., and other tension developing affixations for transferring the tensile stresses to and from the hollow member 101. Further, the method for transferring tension to and from the hollow member 101 may be performed using multiple other methods comprising, for example, affixing alternative headed stud head members (not shown) as substitutes for the deformed rebars 103 and 104 to the hollow member 101, affixing a wire mesh (not shown) to the hollow member 101, affixing a synthetic material (not shown) to the hollow member 101, configuring ridges (not shown) within the hollow member 101, etc.

In an embodiment as exemplarily illustrated in FIGS. 4A-4B, the tension rebars, for example, the corrugated fins 112 and 113 and the bent plates 114 and 115 are welded directly to the opposing sides 101 d and 101 e of the upper portion 101 a of the hollow member 101 of the sleeve device 100 without the rebar connectors 105 and 106 exemplarily illustrated in FIGS. 1A-3. In this embodiment, the tensile stresses are directly transferred to and from the hollow member 101 to the tension rebars, for example, 112, 113 and 114, 115. In an embodiment, a cross section A-A of the hollow member 101 is of a circular geometric shape as exemplarily illustrated in FIGS. 4A-4B.

FIGS. 5A-5B exemplarily illustrate isometric views of different embodiments of the sleeve device 100, showing different cross sections of the hollow member 101. In an embodiment, a cross section B-B of the hollow member 101 is of a square geometric shape as exemplarily illustrated in FIG. 5A. In another embodiment, the cross section C-C of the hollow member 101 is of a rectangular geometric shape as exemplarily illustrated in FIG. 5B.

FIG. 6 exemplarily illustrates a side view of the sleeve device 100 positioned within a reinforced concrete slab 601, showing bending moments 602, tensile stresses 603, and compressive stresses 604 acting on the reinforced concrete slab 601. The bending moments 602, tensile stresses 603, and compressive stresses 604 are indicated by arrows in FIG. 6. The bending moments 602 that are induced in the reinforced concrete slab 601 on the opposing sides 101 d and 101 e of the hollow member 101 are resisted by the tensile stresses 603 in the deformed rebars 103 and 104 and the compressive stresses 604 in the concrete 109 exemplarily illustrated in FIG. 1A. The tensile stresses 603 in the deformed rebars 103 and 104 act in opposing directions through the reinforced concrete slab 601 from the opposing sides 101 d and 101 e of the hollow member 101. The compressive stresses 604 in the concrete 109 act inwardly towards the hollow member 101 at the opposing sides 101 d and 101 e of the hollow member 101, proximal to a lower section 601 a of the reinforced concrete slab 601. The compressive stresses 604 in the concrete 109 and the tensile stresses 603 acting on the opposing sides 101 d and 101 e of the hollow member 101 are balanced out through the outer wall 101 c of the hollow member 101.

FIG. 7A exemplarily illustrate an isometric wireframe view, showing deformed rebars 103 and 104 of the sleeve device 100 in a different orientation within a concrete beam 701. As exemplarily illustrated in FIG. 7A, the concrete beam 701 is positioned below a reinforced concrete slab 601 and is supported by supporting columns 702 and 703 and the reinforced concrete slab 601. FIG. 7B illustrates an enlarged view of a portion marked Y in FIG. 7A. In an embodiment, the deformed rebars 103 and 104 can be rotated and repositioned within the concrete beam 701 to transfer the tensile stresses and moment to and from the deformed rebars 103 and 104 and the hollow member 101 in different ways and in multiple directions, for example, along different axes. The sleeve device 100 can be rotated, for example, at right angles to create a void 102 in a horizontal direction within the concrete beam 701. The sleeve device 100 counteracts the bending moments 704 generated by the supporting columns 702 and 703 on the concrete beam 701 as exemplarily illustrated in FIGS. 7A-7B. As exemplarily illustrated in FIG. 7B, multiple deformed rebars 103 and 104 are connected to the opposing sides 101 d and 101 e of the hollow member 101 using multiple rebar connectors 105 and 106 to increase the bending moment transfer capacity of the sleeve device 100. The sleeve device 100 is used in monolithic poured concrete beams 701 which are positioned proximal to the supporting columns 702 and 703.

FIG. 8 exemplarily illustrates a top plan view, showing splicing of the deformed rebars 103 and 104 of two sleeve devices 100 a and 100 b with top rebars 802 of the reinforced concrete slab 601. As exemplarily illustrated in FIG. 8, two sleeve devices 100 a and 100 b are positioned proximal to a supporting column 804. In an embodiment, the sleeve device 100 a or 100 b transfers the bending moments induced in the reinforced concrete slab 601 by coupling the deformed rebars 103 and 104 to the top rebars 802 among the regular reinforced concrete slab rebars 801 by horizontal splicing. The deformed rebars 103 and 104 are configured to be spliced with the top rebars 802 of the reinforced concrete slab 601 in accordance with a standard rebar tension splice length 803 for transferring the bending moments induced in the reinforced concrete slab 601. With a predefined range of standard rebar tension splice lengths 803 between the deformed rebars 103 and 104 and the top rebars 802, the tensile stresses are transferred to the top rebars 802 and/or to the regular reinforced concrete slab rebars 801 to compensate the moment capacity loss. As used herein, “moment capacity” refers to the capacity of the reinforced concrete slab 601 to resist bending moment. When loads are applied to the reinforced concrete slab 601, the reinforced concrete slab 601 tends to deform and induces a tensile strain in the deformed rebars 103 and 104 through a bond between the concrete 109 exemplarily illustrated in FIG. 1A, and the deformed rebars 103 and 104. The tensile stresses in the deformed rebars 103 are then transferred through the relatively stiffer hollow member 101 to the opposing side 101 e of the hollow member 101. That is, the tensile stresses due to the bending moments are transferred to the first deformed rebar 103 on one opposing side 101 d of the hollow member 101, then through the hollow member 101, to the second deformed rebar 104 on the other opposing side 101 e of the hollow member 101, and then to the top rebars 802 among the regular reinforced concrete slab rebars 801, that are spliced with the deformed rebars 103 and 104.

FIG. 9A exemplarily illustrates an isometric view of multiple sleeve devices 100 a, 100 b, and 100 c positioned in a reinforced concrete slab 601 supported by a supporting column 901. FIG. 9B illustrates an enlarged view of a portion marked Z in FIG. 9A. Each of the sleeve devices 100 a, 100 b, and 100 c comprises the hollow member 101, the deformed rebars 103 and 104, and the rebar connectors 105 and 106 as exemplarily illustrated in FIGS. 1A-3. The sleeve devices 100 a, 100 b, and 100 c are used in concrete construction, for example, in cast-in-place reinforced concrete slabs 601. A user places each hollow member 101 at a predetermined position in the bottom formwork 108 as exemplarily illustrated in FIG. 1A. The sleeve devices 100 a, 100 b, and 100 c are positioned adjacent to each other on the bottom formwork 108 with the upper portion 101 a of each hollow member 101 on the top of the bottom formwork 108 of the reinforced concrete slab 601. As exemplarily illustrated in FIGS. 9A-9B, the sleeve device 100 c is aligned perpendicular to the other two sleeve devices 100 a and 100 b. The deformed rebars 103 and 104 are spliced with the top rebars 802 among the regular reinforced concrete slab rebars 801 exemplarily illustrated in FIG. 8. The mounting rings 107 fasten the sleeve devices 100 a, 100 b, and 100 c to the bottom formwork 108 that defines the reinforced concrete slab 601 and secure the sleeve devices 100 a, 100 b, and 100 c in place. Concrete 109 exemplarily illustrated in FIG. 1A, is then poured onto the bottom formwork 108 and cast around the hollow member 101 of each of the sleeve devices 100 a, 100 b, and 100 c. Each hollow member 101 defines a void 102 in the reinforced concrete slab 601 formed inside the bottom formwork 108 and the void 102 remains free of concrete 109.

After the concrete 109 is cast around the sleeve devices 100 a, 100 b, and 100 c, the sleeve devices 100 a, 100 b, and 100 c are embedded in the reinforced concrete slab 601 and form a component of the reinforced concrete slab 601. The tensile stresses due to the bending moments in the reinforced concrete slab 601 are transferred to the first deformed rebar 103 on an opposing side 101 d of the hollow member 101 exemplarily illustrated in FIG. 2. The tensile stresses are then transferred through the relatively stiffer hollow member 101 to the second deformed rebar 104 on the other opposing side 101 e of the hollow member 101 exemplarily illustrated in FIG. 2. The deformed rebars 103 and 104 that are spliced with the top rebars 802 among the regular reinforced concrete slab rebars 801 balance the tensile stresses due to the bending moments induced in the reinforced concrete slab 601.

As exemplarily illustrated in FIGS. 9A-9B, when a penetration or a void 102 is made in the reinforced concrete slab 601 located near a supporting column 901, the reinforced concrete slab 601 undergoes a moment capacity loss and necessitates a moment capacity check of the reinforced concrete slab 601. The sleeve device 100 a, or 100 b, or 100 c disclosed herein compensates for the moment capacity loss due to the creation of the void 102 by transferring tensile stresses in the mature reinforced concrete slab 601.

FIG. 10 illustrates a method for transferring bending moments induced in a reinforced concrete slab 601 exemplarily illustrated in FIG. 6. A sleeve device 100 comprising a hollow member 101 and tension rebars configured, for example, as deformed rebars 103 and 104 as exemplarily illustrated in FIGS. 1A-9B is provided 1001. The deformed rebars 103 and 104 of the sleeve device 100 are spliced 1002 with top rebars 802 of the reinforced concrete slab 601 exemplarily illustrated in FIG. 8, in accordance with a standard rebar tension splice length 803, for example, by horizontal splicing for transferring the bending moments induced in the reinforced concrete slab 601. Concrete 109 is poured around an outer wall 101 c of the hollow member 101 to create 1003 a void 102 in the reinforced concrete slab 601. The tensile stresses due to the bending moments induced in the reinforced concrete slab 601 are transferred 1004 to a first deformed rebar 103 on one opposing side 101 d of the hollow member 101 and the upper portion 101 a of the hollow member 101. The transferred tensile stresses from the upper portion 101 a of the hollow member 101 are then transferred 1005 to a second deformed rebar 104 on the other opposing side 101 e of the hollow member 101. The transferred tensile stresses from the second deformed rebar 104 are transferred 1006 to the top rebars 802 of the reinforced concrete slab 601 spliced with the deformed rebars 104. The tensile stresses 603 in the deformed rebars 103 and 104 and the compressive stresses 604 in the concrete 109 exemplarily illustrated in FIG. 6, resist the bending moments 602 in the reinforced concrete slab 601. The tensile stresses 603 from the deformed rebars 103 and 104 are bridged by transferring the tensile stresses 603 in the deformed rebars 103 and 104 on the opposing sides 101 d and 101 e of the hollow member 101 into the hollow member 101, and balancing out the tensile stresses 603 acting on the opposing sides 101 d and 101 e of the hollow member 101 through the outer wall 101 c of the hollow member 101.

The sleeve device 100 exemplarily illustrated in FIGS. 1A-3 is constructed of any suitable material capable of transferring the loads. The components of the sleeve device 100, for example, the hollow member 101, the deformed rebars 103 and 104, and the rebar connectors 105 and 106 are rearranged in multiple orientations to accommodate penetrations in the reinforced concrete slab 601. The sleeve device 100 can be located anywhere in the reinforced concrete slab 601, for example, near supports such as the supporting column 901 exemplarily illustrated in FIG. 9A, and walls. The sleeve device 100 can also be located in a concrete beam 701 as exemplarily illustrated in FIG. 7A.

The sleeve device 100 can be made, for example, in a shop. In an example of making the sleeve device 100, a steel fabricator cuts a steel pipe to an appropriate length to create the hollow member 101. The steel fabricator then shop welds mechanical couplers or the rebar connectors 105 and 106 to each side 101 d and 101 e of the upper portion 101 a or the top of the hollow member 101. The deformed rebars 103 and 104 are connected to the rebar connectors 105 and 106 on the opposing sides 101 d and 101 e of the hollow member 101 as exemplarily illustrated in FIGS. 1A-3. The rebar connectors 105 and 106 are prefabricated. In an embodiment, the deformed rebars 103 and 104 are welded directly to the opposing sides 101 d and 101 e of the hollow member 101 without connecting the rebar connectors 105 and 106 to each side 101 d and 101 e of the upper portion 101 a or the top of the hollow member 101. The mounting rings 107 or form tabs are welded to the bottom plane 101 f of the hollow member 101.

The sleeve device 100 exemplarily illustrated in FIGS. 1A-3 is used, for example, in flat plate cast-in-place concrete construction in two way slabs, one way slabs, slabs with beams, or any other type of slab system. The sleeve device 100 is further used, for example, in beams either vertically or horizontally, on concrete walls or columns, in brackets, capitals, corbels, buttresses, ramps, stairs, or any other portion of building transferring loads. The sleeve device 100 is further used, for example, in concrete on a steel deck, in precast members such as bridge components, marine components, facades, plank, T shaped bridge components, double T bridge components, etc. The sleeve device 100 is further used in combination with pre-stressing or post tensioning.

The foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention disclosed herein. While the invention has been described with reference to various embodiments, it is understood that the words, which have been used herein, are words of description and illustration, rather than words of limitation. Further, although the invention has been described herein with reference to particular means, materials, and embodiments, the invention is not intended to be limited to the particulars disclosed herein; rather, the invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may effect numerous modifications thereto and changes may be made without departing from the scope and spirit of the invention in its aspects. 

I claim:
 1. A sleeve device for transferring bending moments induced in a reinforced concrete slab, said sleeve device comprising: a generally hollow member positioned on and fastened to a bottom formwork defining said reinforced concrete slab, said generally hollow member configured to create a void in said reinforced concrete slab by pouring of concrete around an outer wall of said generally hollow member, said generally hollow member further configured to transfer compressive stresses across a bottom of said generally hollow member and tensile stresses through tension rebars and an upper portion of said generally hollow member; and said tension rebars connected to opposing sides of said upper portion of said generally hollow member, said tension rebars are configured to be spliced with top rebars of said reinforced concrete slab in accordance with a rebar tension splice length for transferring said bending moments induced in said reinforced concrete slab, wherein said bending moments in said reinforced concrete slab are resisted by said tensile stresses in said tension rebars and said compressive stresses in said concrete, and wherein said tensile stresses in said tension rebars on said opposing sides of said generally hollow member are transferred into said generally hollow member, and said tensile stresses acting on said opposing sides of said generally hollow member are balanced out through said outer wall of said generally hollow member, thereby bridging said tensile stresses from said tension rebars.
 2. The sleeve device of claim 1, wherein said tension rebars are welded directly to said opposing sides of said upper portion of said generally hollow member, wherein said tension rebars are configured to directly transfer said tensile stresses to and from said generally hollow member.
 3. The sleeve device of claim 1, further comprising rebar connectors operably connected on said opposing sides of said upper portion of said generally hollow member, wherein said rebar connectors are configured to fixedly connect said tension rebars to said opposing sides of said upper portion of said generally hollow member.
 4. The sleeve device of claim 1, wherein a cross section of said generally hollow member is of a geometric shape comprising at least one of a circular shape, a square shape, and a rectangular shape.
 5. The sleeve device of claim 1, wherein said generally hollow member is of a generally cylindrical shape.
 6. The sleeve device of claim 1, wherein said tension rebars are further configured to be rotated and repositioned to transfer said tensile stresses to and from said tension rebars and said generally hollow member in a plurality of directions.
 7. The sleeve device of claim 1, wherein said tension rebars are configured as deformed rebars to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member.
 8. The sleeve device of claim 1, wherein said tension rebars are configured as corrugated fins to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member.
 9. The sleeve device of claim 1, wherein said tension rebars are configured as bent plates to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member.
 10. A method for transferring bending moments induced in a reinforced concrete slab, said method comprising: providing a sleeve device comprising: a generally hollow member positioned on and fastened to a bottom formwork defining said reinforced concrete slab; and tension rebars connected to opposing sides of an upper portion of said generally hollow member; splicing said tension rebars of said sleeve device with top rebars of said reinforced concrete slab in accordance with a rebar tension splice length for transferring said bending moments induced in said reinforced concrete slab; creating a void in said reinforced concrete slab by said generally hollow member of said sleeve device by pouring concrete around an outer wall of said generally hollow member; transferring tensile stresses due to said bending moments induced in said reinforced concrete slab to a first of said tension rebars on one of said opposing sides of said generally hollow member and said upper portion of said generally hollow member; transferring said transferred tensile stresses from said upper portion of said generally hollow member to a second of said tension rebars on another one of said opposing sides of said generally hollow member; and transferring said transferred tensile stresses from said second of said tension rebars to said top rebars of said reinforced concrete slab spliced with said tension rebars, wherein said bending moments in said reinforced concrete slab are resisted by said tensile stresses in said tension rebars and compressive stresses in said concrete, and wherein said tensile stresses in said tension rebars on said opposing sides of said generally hollow member being transferred into said generally hollow member, and said tensile stresses acting on said opposing sides of said generally hollow member are balanced out through said outer wall of said generally hollow member, thereby bridging said tensile stresses from said tension rebars.
 11. The method of claim 10, wherein said tension rebars are welded directly to said opposing sides of said upper portion of said generally hollow member to directly transfer said tensile stresses to and from said generally hollow member.
 12. The method of claim 10, wherein said tension rebars are fixedly connected to said opposing sides of said upper portion of said generally hollow member using rebar connectors operably connected on said opposing sides of said upper portion of said generally hollow member.
 13. The method of claim 10, further comprising coupling said tension rebars to said reinforced concrete slab rebars via horizontal splicing for transferring said bending moments induced in said reinforced concrete slab.
 14. The method of claim 10, wherein a cross section of said generally hollow member of said sleeve device is of a geometric shape comprising at least one of a circular shape, a square shape, and a rectangular shape.
 15. The method of claim 10, wherein said generally hollow member is of a generally cylindrical shape.
 16. The method of claim 10, further comprising rotating and repositioning said tension rebars to transfer said tensile stresses to and from said tension rebars and said generally hollow member in a plurality of directions.
 17. The method of claim 10, wherein said tension rebars are configured as one of deformed rebars, corrugated fins, and bent plates to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member. 